Sound channels for audio reproduction may typically include channels associated with a particular source direction. A monophonic (“mono”) sound channel may be reproduced with a single loudspeaker. Monophonic sound may thus be perceived as originating from the direction in which the speaker is placed in relation to a listener. Stereophonic (“stereo”) uses at least two channels and loudspeakers and may thus increase a sound stage over monophonic sound.
Stereo sound may include distinct audio content on each of two “left” and “right” channels, which may each be perceived as originating from the direction of each of the speakers. Stereo (or mono) channels may be associated with a viewing screen, such as a television, movie screen or the like. As used herein, the term “screen channels” may refer to audio channels perceived as originating from the direction of a screen. A “center” screen channel may be included with left and right stereo screen channels.
As used herein, the term “multi-channel audio” may refer to expanding a sound stage or enriching audio playback with additional sound channels recorded for reproduction on additional speakers. As used herein, the term “surround sound” may refer to using multi-channel audio with sound channels that essentially surround (e.g., envelop, enclose) a listener, or a larger audience of multiple listeners, in relation to a directional or dimensional aspect with which the sound channels are perceived.
Surround sound uses additional sound channels to enlarge or enrich a sound stage. In addition to left, right and center screen channels, surround sound may reproduce distinct audio content from additional speakers, which may be located “behind” a listener. The content of the surround sound channels may thus be perceived as originating from sources that “surround,” e.g., “are all around,” the listeners. Dolby Digital™ (also called AC-3) is a well known successful surround sound application. Surround sound may be produced with five loudspeakers, which may include the three screen channels left, center and right, as well as a left surround channel and a right surround channel, which may be behind a view of the screen associated with the screen channels. A separate channel may also function, e.g., with a lower bit rate, for reproducing low frequency effects (LFE).
Approaches described in this section could be pursued, but have not necessarily been previously conceived or pursued. Unless otherwise indicated, it should not be assumed that any approaches described in this section qualify as prior art merely by virtue of their inclusion herein. Similarly, issues identified with respect to one or more approaches should not be assumed to have been recognized in any prior art on the basis of this section, unless otherwise indicated.